Requirements:
- WiiU with 2.1.0/2.1.3/3.0.1/3.1.0/4.0.0/4.0.2/4.0.3/4.1.0/5.0.0/5.1.0/5.1.1/5.1.2/5.2.0/5.3.0/5.3.1/5.3.2/5.4.0/5.5.0 System Menu (versions lower than 2.1.0 do not have vWii installed - not tested with greater versions)
- SD NON-HC (better if blank/clean to avoid potentially fatal installation of old Wii non-compatible WADs - 4Gb but better 2Gb or smaller; 4Gb can be HC and HC cards will not work; 2GB are surely not HC)
- Original Lego Batman Wii game (look for notes below for other supported games)
- You must play at least 1 time with LEGO BATMAN in vWii mode

HackMii Installer (at least version 1.2 - alternative download link here); download and extract \hackmii_installer_v1.2 folder content in SD root <-- (to be launched when using the above exploit in order to install The Homebrew Channel, a very useful homebrew)

Configurable USB Loader Mod; download and copy the latest .dol file in SD :\apps\USBLoader renaming it to boot.dol ; if something is not working for you it is alternatvely possible the use of Wiiflow or USBLoader GX, other 2 great loaders ! Remember to use the loaders .DOL file and NOT the WAD installation channel and/or forwarder ! Old Wii WADs may lead you to brick the vWii mode if not correctly recompiled for vWii !). <-- (Loaders are needed to launch game backups)

3) Execute exploit/Install HBC
Go back to vWii menu ad launch the game -> load the saved game (100%) and you will found yourself in the bat-cave; take the right elevator -> enter the trophy room and get into the upper-left door to go to "Wayne Manor" -> with nunchuck bring the cursor over the enabled character in the lowest row (see minute 1:03 of the following video) to execute the exploit (boot.elf). Follow on-screen procedure to complete HBC Install.

(video found on youtube searching for "bathaxx" - thanks to the original author !)

5) Backup vWii mode NAND content
Start HBC -> launch latest version of the great Dump Mii NAND tool (by Maxternal) tool;
the automatic dump procedure will last from 20 to 60 minutes (in my experience it depends on the SD card you are using); the files (nand.bin and keys.bin) will be dumped in sd:/apps/DumpMiNND/ folder; at the end of the dumping procedure your WiiU will reboot.

Edit by Cyan:6) Dump your IOS for eventual vWii semi-brick fix (optional step but recommended !)
Launch YetAnotherBlueDumpMod
Go to System Titles and dump each IOS individually to a wad.
When prompted to fakesign the ticket or TMD, say No to both. It's a tedious process, but it could save a lot of trouble in the future.

If you don't have CLEAN IOS, you won't be able to fix semi-bricked vWii.
You can't create wads from a NAND dump or from using ShowMiiWads. You NEED to use YetAnotherBlueDumpMod.
so please, don't skip this step (but you can do it after step 7 if you want).

2 - DO NOT PLAY WITH IOS and cIOS both for vWii and real Wii, they are DIFFERENT and use a Wii IOS or cIOS with vWii (and vice versa) CAN BRICK YOUR vWii !!!

3 - Do not play with System Menu, channels or vWii titles to avoid unwanted vWii bricks !

4 - Some 2.5" external hard drivers can need additional power supply (even if they were perfectly working in a real Wii); try to use an Y cable to power them up:there are different Y cables depending on your 2.5" Hard Disk USB interface:WHILE CHOOSING THE CORRECT Y CABLE BE ALSO VERY CAREFUL AT IDENTIFYING MICRO USB 3.0 A or B MALE CONNECTOR BECAUSE Micro A Male DOES NOT FIT IN Micro B female (for what I know Micro A female-only does not exist, only Micro B-female or Micro AB-female exist):

5 - USB port to use is the UPPER one (considering the WiiU laying on a table as a standard DVD player):
(you can use the lower one for additional optional Y-Cable power supply)

6a - If you receive an error (dump error) using Configurable USB Loader (both with alt or normal cIOS version):

6b - If you have black screen (always with CFG USB Loader) starting a game that was perfectly working BEFORE 4.x update (es. Wii Fit/Wii Fit Plus) try to set the "Video" option to "Game Default" (and not "System Def.") as showed in the following picture:

7 - If you connect your external USB games-backup-hard-drive before turning WiiU on you will receive the annoyng "Format USB Disk" screen:
- Here is UStealth solution by brilliant jayjay123 !
- Alternatively you can press B button at power on bypassing WiiU System Menu and entering directly in vWii mode.

8 - After updating to firmware 4.0.0 you may see HBC forced to 4:3:
Here is a WORKAROUND by the great JoostinOnline !

OPTIONAL STEPS

=================
cIOS236 INSTALLATION
=================
This cIOS can be necessary to launch some homebrews (which doesn't use ahbprot).

1) Download IOS36-64-v3864.wad (look for "sendspace kl6o78" and download the .rar file from sendspace - thanks to someone of that forum for that hint), extract the .WAD and place it in your SD root

nice, only problem i have is if nintendo release a firmware update in the future will it brick the vwii as the cios has been modified, also when do you insert the hard drive when you load config usb loader up? you obviously can't do it on the vwii menu.

The optional step extract key and dump nand is a must have done step before you begin.
You should do this after you installed the hombrew channel.
If for whatever reason like faulty sd card or so the installation fails you will brick.
You need the keys and nand if you wan`t to undo your brick.

The optional step extract key and dump nand is a must have done step before you begin.
You should do this after you installed the hombrew channel.
If for whatever reason like faulty sd card or so the installation fails you will brick.
You need the keys and nand if you wan`t to undo your brick.

It's better if you link each program separately, users can take the one they are missing (you can make a pack too, but link programs separately too)
Do not pack a USBloaders (they are evolving fast, the pack will be outdated quickly, and it will take less space, users better get the latest release)
Pictures watermarked from another websites? logic sunrise allowed you too? (yeah, I know it's just google>guide>translation)

Wouldn't step 0 (why 0? not 1?) be "extract the content on a SD card"?
And it should be a clean/formated SD, to prevent bricking vWii by having Wii's WAD on it.

like said, you better dump the NAND and the keys FIRST, before adding system titles, unfortunately you need to install HBC before dumping it so it's not a clean one, but without an hardware it can't be done.

I know, you just translated it, and it's written like this in the original guide.

Noobyn00b guide are great, but I don't like them.
they don't teach anything to users. it's just "copy that, press button, done".
users should learn and understand what they are doing, what it does, etc.

example: You never said "This step will install the Homebrew Channel". Users with the Homebrew channel don't need to do it again.
I know it's just a translation of another guide, but it miss things and doesn't explain anything. This is a bad one for users in my opinion, but they are free to follow it if they prefer a "press one button" guide.

i'm glad you have these steps in here, but they should not be optional and should probably be the first steps. these are the only recovery avenues we have currently. at a minimum EVERYONE should be grabbing their keys. i guess the nand fs dump could be optional... but not the keys...